1. Field of the Invention
The present invention pertains to medical devices and methods, and more particularly, to a method and catheter system for accessing the central lumen of a blood vessel from extraluminal space.
2. Description of the Prior Art
There have been many procedures and systems for treating vascular or venous obstructions that are occluded with atheroma, plaque or calcific material, and are often referred to as vascular chronic total occlusion. In the past, such cardiovascular diseases were treated using a dramatic and painful surgical bypass procedure. However, a recent development of catheter-based interventions is less traumatic, and shows better success rates and long term patency.
The catheter-based interventional procedures require that a guidewire is positioned through such an occlusion in a distal central lumen. In many instances, guidewire placement in the central distal lumen is difficult or almost impossible, mostly due to hard occlusive material or the inability to define a vessel path. Often, during such procedures, a guidewire deflects from the occlusion and penetrates into an extraluminal space (i.e., subintimal or outside the vessel). Frequently, a guidewire might perforate a vessel and end up outside of the vessel. While such perforations are very dangerous in certain circulations (e.g., in the brain and the heart), such perforations are less risky in peripheral arterial circulations and in most of the venous system due to the muscular tissue surrounding these areas.
Once in an extraluminal space, between layers of the vessel, it is difficult or often impossible to re-enter a guidewire into the central lumen even with the use of ancillary deflecting catheters or devices. In such cases, a catheter-based intervention cannot be performed and patient well being relies on more complex and painful surgical intervention.